known that the Trade winds blow but faint for some
distance within their limits, and are therefore easily stopt by a wind
from the Contrary direction. It is likewise known that these limits are
subject to vary several degrees, not only at different seasons of the
Year, but at one and the same season. Another reason why I think that
these South-West winds are not caused by the nearness of any large Track
of land, is in their being always accompanied with a large swell from the
same Quarter, and we find a much greater surf beating upon the Shores of
the South-West sides of the Islands situated just within the Limits of
the Trade winds than upon any other part of them.

The tides are perhaps as inconsiderable in these Seas as in any part of
the world. A South or South by West moon makes high water in Royal Bay,
but the water does not rise upon a perpendicular above 10 or 12 inches,
except on some very Extraordinary occasions.

The variation of the Compass I found to be 4 degrees 46 minutes Easterly,
this being the mean result of a great number of Trials made by 4 of Dr.
Knight's needles belonging to the Azimuth Compasses, all of which I
judged to be good ones, and yet when applied to the Meridian line I found
them not only differ one from another sometimes a degree and a half; but
the same needle would differ from itself more or less, the difference
sometimes amounting to half a degree, both at the same time and on
differant days. This will in a great measure account for the seeming
errors that may, upon a nice examination, appear to have been made in
observing the Variation inserted in the Course of this Journal. This
variableness in Magnetick Needles I have many times and in many places
experienced both ashore and on board of Ships, and I do not remember of
ever finding two Needles that would agree exactly together at one and the
same time and place, but I have often found the same Needle agree with
itself for several Trials made immediately one after another.* (* These
discrepancies result from imperfections in the suspension and mounting of
the needles, and are only absent in instruments too delicate for ordinary
sea service.) However, all this is of no sort of consequence to
Navigation, as the Variation of the Compass can always be found to a
degree of accuracy more than sufficient for all nautical Purposes.

I have before hinted that these People have an Extensive knowledge of the
Islands situated in these Seas. Tup